Method of checking authenticity of sheet with built-in electronic circuit chip

ABSTRACT

A method of checking sheets as to forgery thereof, the sheet being provided with an electronic circuit chip from which information can be read cut or written and having visible information. The method includes a step of encrypting the visible information of the sheet and storing the encrypted visible information in the electronic circuit chip, and a step of determining discriminatively the authenticity of the sheet by comparing the visible information of the sheet with the information stored in the electronic circuit chip.

This is a continuation application of U.S. Ser. No. 09/857,271, filedNov. 27, 2001 now U.S. Pat. No. 6,659,353 which is a 371 ofPCT/JP99/06798 filed Dec. 13, 1999.

TECHNICAL FIELD

The present invention relates to management of sheets having visibleinformation.

BACKGROUND ART

For preventing forgery of sheets such as valuable papers, bank notes,documents and the like which carry visible information, there haveheretofore been adopted such measures as printing a fine or detailedpictorial pattern and/or characters or the like on the sheet, pasting ahologram on the sheet or impressing a watermark in the sheet whiledetails of these measures being kept in secrecy in an attempt to make itdifficult to forge or counterfeit the sheet. Further, inspection of thesheet as to forgery can be carried out by comparing the opticalinformation of printing position on the sheet, fineness of patternlines, color density or brightness, etc. with the correspondinginformation of the genuine sheet.

Furthermore, sheet management such as counting of the number(s) of thesheets has heretofore been performed manually or physically with amachine on a sheet-by-sheet basis.

At present, however, technological progress in this field has made itpossible to impress the watermark, hologram and the like, and now theinformation such as mentioned previously can be printed with a highaccuracy which is comparable to that of the genuine sheet even thoughthe printing procedure may differ. Such being the circumstances,difficulty is encountered in detecting the forgery solely by relying onthe comparison of the optical information.

Additionally, it is noted that in the case of bonds of a same species,the optical information of pictorial pattern or the like which can beused for checking or detecting the forgery remains identical for all thebonds and that the information inherent to the bond such as the bond IDnumber or the like is not used for the inspection of the forgery.Consequently, once a pictorial pattern of a given bond wascounterfeited, there may arise such risky situation that a great numberof bonds printed with the counterfeit pattern and having the inherentinformation such as the ID numbers rewritten are fabricated on amass-production scale or the contents of the bonds are easilycounterfeited.

Besides, in conjunction with such management of the sheets as countingof the number thereof, etc., it is noted that the volume, species,sizes, etc. of the sheets which can be handled at one stretch arelimited although it depends on the scale of the managing system.Consequently, a time-consuming troublesome procedure or a large scale ofthe managing system is required for the management of a large number ofsheets. On the other hand, it is also known to manage articles byaffixing so-called radio tags onto articles to be managed. However,reliability of the congestion controlling function of the conventionalradio tags generally used at present is not so high. Accordingly,employment of the radio tag is not suited for the cases where very highreliability is required as in the case of management of the valuablepapers, bank notes and so forth.

DISCLOSURE OF INVENTION

Thus, it is an object of the present invention to provide a structure ofsheets having visible information such as bonds, exchange tickets, papercurrencies, various labels, documents or the like which allows thecounterfeit, if any, to be detected without difficulty, a method ofmanufacturing such sheets, an apparatus for manufacturing the same, amethod of checking the sheets as to the forgery, and an apparatus fordetecting the forged or counterfeit sheets.

Moreover, it is another object of the present invention to provide asystem capable of handling speedily once a large number of sheets undermanagement which differ from one another in respect to the species andthe size with high reliability by using a small-scale apparatus, amethod of implementing the same and a sheet therefor.

For achieving the object mentioned above, the present invention teachesthat an electronic circuit chip from or in which information can be reador written is incorporated in the sheet. Further, it is taught thatinformation inherent to each sheet is encrypted or a digital signatureis generated for affixation, whereon the encrypted information or thedigital signature or both of them are stored in the above-mentionedelectronic circuit chip or another storing means.

At this juncture, it is contemplated with the phrase “another storingmeans” to mean another electronic circuit chip mounted on one and thesame sheet or a storage medium (e.g. memory, hard disk or the like)provided externally of the sheet. When the information is to be storedin the storage medium provided externally of the sheet, the informationshould be stored in the state associated with the ID (identification)information stored in the chip on the sheet.

As the intrinsic or inherent information to be stored, there may bementioned, for example, visible information which the sheetintrinsically or inherently presents (inclusive of the ID numberdiffering from one to another sheet) or physical/chemical information ofthe electronic circuit chip. Further, shapes or geometrical factors ofdistinctively discernible sheet constituent elements, physical orchemical information of other discernible materials or elements insertedor embedded in the sheet can be used as the inherent information whichis intrinsic to the sheet. Besides, relative positions of the sheetconstituent element(s) and the discernible material or element relativeto the electronic circuit chip can equally be used as the inherentinformation. Thus, by comparing the information available from theelectronic circuit chip or the external storing means with theinformation acquired by actually scanning the sheet, it is possible tocheck the sheet as to the forgery thereof.

Further, the sheet according to the present invention incorporates anelectronic circuit chip, i.e., so-called built-in electronic circuitchip, which includes a means for transmitting intermittently signalsindicative of the information inherent to the individual sheets(hereinafter also referred to as the sheet-inherent information),respectively, with every random transmission interruption period and ameans for stopping the transmission in response to a stop command. Onthe other hand, the management system according to the present inventionis designed to receive the sheet-inherent signals from the individualsheets to thereby manage a plurality of sheets concurrently.

More specifically, upon reception of the sheet-inherent signal from agiven sheet, the management system performs recognition processing forthat sheet to thereby send a stop command which is valid only for thatsheet. In case the management system can not correctly receive aplurality of signals sent concurrently, the management system does notissue the stop command but waits for till the signals inherent to theindividual sheets, respectively, are sent again. The signals sent fromall the sheets can be received within a predetermined time period. Inthis way, the sheets can be managed. Additionally, species of the sheetscan discriminatively be specified on the basis of the informationinherent to the individual sheets. Furthermore, by using a means fortransmitting a ratio wave over a limited coverage range and byperforming recognition processing for the sheets while moving theabove-mentioned means along the direction in which the sheets arestacked, the ratio or frequency at which the signals are simultaneouslysent from a plurality of sheets can be reduced. Thus, management of thesheets can be carried out at a high speed with enhanced reliability.

Thus, the forgery checking method according to the present invention isdesigned for checking a sheet such as bond, document or the like as toforgery thereof, each of which sheets is provided with an electroniccircuit chip from or in which information can be read out or written andhas visible information, the method being characterized in that thevisible information of the sheet mentioned above is encrypted to bestored in the electronic circuit chip mentioned above, and thatauthenticity of the sheet is decided by making use of the visibleinformation of the sheet and the information stored in the electroniccircuit chip.

More specifically, the method is characterized by making decision as tothe authenticity of the sheet by comparing the visible information ofthe sheet with the information stored in the electronic circuit chip.

Further, the forgery checking method according to the present inventionresides in a method of checking the sheet as to forgery thereof bymaking use of the information acquired by scanning the sheet and theinformation stored in the above-mentioned electronic circuit chip, whichmethod is characterized in that physical or chemical information ofsheet constituent elements which can be discerned externally of thesheet is encrypted to be stored in the electronic circuit chip.

Furthermore, the forgery checking method according to the presentinvention resides in a method of checking the sheet as to forgerythereof by making use of the information acquired by scanning the sheetand the information stored in the above-mentioned electronic circuitchip, which method is characterized in that relative positioninformation of the above-mentioned sheet constituent elements relativeto the electronic circuit chip is encrypted to be stored in theelectronic circuit chip.

Further, the forgery checking method according to the present inventionresides in a method of checking the sheet as to forgery thereof bymaking use of the information acquired by scanning the sheet and theinformation stored in the above-mentioned electronic circuit chip, whichmethod is characterized in that the above-mentioned information anddigital signature information for that information are stored in theelectronic circuit chip.

Furthermore, the forgery checking method according to the presentinvention resides in a method of checking the sheet as to forgerythereof by making use of the information acquired by scanning the sheetand the information stored in the above-mentioned electronic circuitchip, which method is characterized in that the above-mentionedinformation is stored in at least two electronic circuit chipsincorporated in a single sheet, that the sheet is decided to be a forgedone when difference is found in a greater number of pieces ofinformation than a proper threshold value which is determined on thebasis of information elements such as the number of pieces ofinformation stored in the electronic circuit chip, accuracy and thelike, and that the sheet is decided to be an authentic one whendifference is found in a number of pieces of said information which isequal to or smaller than the above-mentioned threshold value.

Further, the forgery checking method according to the present inventionresides in a method of checking the sheet as to forgery thereof bymaking use of the information acquired by scanning the sheet and theinformation stored in the above-mentioned electronic circuit chip, whichmethod is characterized in that the electronic circuit chip is mountedon the sheet at a random position thereof, that the above-mentionedinformation is acquired by scanning the sheet after mounting of theelectronic circuit chip, and that the above-mentioned information isencrypted or alternatively a digital signature is generated and affixedto the above-mentioned information or alternatively the above-mentionedinformation is encrypted with a digital signature being generated to beaffixed to the encrypted information and then stored in the electroniccircuit chip.

Furthermore, the forgery checking method according to the presentinvention resides in a method of checking the sheet as to forgerythereof by making use of the information acquired by scanning the sheetand the information stored in the above-mentioned electronic circuitchip, which method is characterized in that information inherent to theelectronic circuit chip is stored in that electronic circuit chip, andthe above-mentioned information to be stored in the above-mentionedelectronic circuit chip is stored in another storing means differingfrom the above-mentioned electronic circuit chip while establishingcorrespondence with information inherent to the above-mentionedelectronic circuit chip.

Additionally, a sheet management system provided by the presentinvention is characterized by a means for receiving signals from sheetshaving respective electronic circuit chips mounted thereon, each of theelectronic circuit chips being comprised of a means for transmittingintermittently a sheet-inherent signal with every random transmissioninterruption periods and a means for stopping the transmission inresponse to reception of a stop command, a means for emitting a radiowave over a limited coverage while being moved along a direction inwhich the sheets are stacked, and a means for performing identificationof the sheet upon reception of the signal from that sheet to therebysend the stop command valid only for that sheet, while waiting for apredetermined time unless the signal is received.

Incidentally, the phrase “physical or chemical information” of theelectronic circuit chip and the sheet constituent elements used in thedescription of the present invention includes information indicatingtheir respective features such as dimensions, masses, materials and thelike.

Additionally, the phrase “visible information” used in the descriptionof the present invention includes information indicated visibly byprint, watermark, surface unevenness, pasted thing, display of a displayelement or the like. Further, the visible information may also subsumesuch information which can be discerned by touch.

Furthermore, the term “sheet” used in the description of the presentinvention connotes a card or the like having a thickness and rigidity.

Further, the term “forgery” or “counterfeit” used in the description ofthe present invention subsumes substitution or reproduction.

Furthermore, the term “management” used in the description of thepresent invention subsumes counting of the number of sheets,discrimination of the species, summing of face amounts of valuablepapers and so forth.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a circuit implemented in the form of anelectronic circuit chip and a sheet on which the circuit is mountedaccording to a first embodiment of the present invention.

FIG. 2 is a view showing a configuration of a manufacturing apparatusfor manufacturing a forged sheet according to the first embodiment ofthe present invention.

FIG. 3 is a flow chart for illustrating a procedure of manufacturing aforged sheet according to the first embodiment of the present invention.

FIG. 4 is a view showing a hardware structure of a forgery checkingsystem according to the first embodiment of the present invention.

FIG. 5 is a view showing a software structure of the forgery checkingsystem according to the first embodiment of the present invention.

FIG. 6 is a flow chart for illustrating a forged sheet detectingprocedure according to the first embodiment of the present invention.

FIG. 7 is a view showing sheet constituent elements and relativeposition information of the sheet constituent elements relative to anelectronic circuit chip according to a second embodiment of the presentinvention.

FIG. 8 is a flow chart for illustrating a procedure of manufacturing aforged sheet according to the second embodiment of the invention.

FIG. 9 is a flow chart for illustrating a forged sheet detectingprocedure according to a third embodiment of the present invention.

FIG. 10 is a flow chart for illustrating a forged sheet detectingprocedure according to a fourth embodiment of the present invention.

FIG. 11 is a view showing sheets and a configuration of a sheetmanagement system according to a sixth embodiment of the presentinvention.

FIG. 12 is a view showing a structure of the sheet according to thesixth embodiment of the present invention.

FIG. 13 is a flow chart for illustrating a sheet management procedureaccording to the sixth embodiment of the present invention.

FIG. 14 is a flow chart for illustrating a forged sheet detectingprocedure according to a fifth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

In the following, a first embodiment of the present invention will bedescribed.

At first, reference is made to FIG. 1 which shows a sheet havinginformation visibly recorded on a surface thereof, an electronic circuitchip mounted on the sheet and elements designed for performing theinformation read-out operation for the electronic circuit chip.

In the figure, reference numeral 11 denotes a sheet having an electroniccircuit chip mounted thereon, wherein the sheet has a surface printedwith information 12. Numeral 13 denotes the electronic circuit chip forwhich information read-out operation can be performed. The electroniccircuit chip is implemented by integrating an electronic circuit on asilicon chip. A capacitor 14 and an antenna 15 serve as the elements forallowing the information read-out operation to be performed for theelectronic circuit chip 13 in a contactless manner relative to the sheet11. Stored in the electronic circuit chip 13 is the informationintrinsic to the sheet 11 or the electronic circuit chip 13 or thecombination thereof.

When a radio wave is applied externally to the sheet 11, an electriccurrent is induced in the antenna 15 under the effect of this radiowave, as a result of which electric charges are stored in the capacitor14. Thus, the electronic circuit chip 13 is put into operation to carryout communication of the information through the medium of the antenna15.

Incidentally, in the case of the instant embodiment of the invention,the circuit is implemented for the contactless communication. However,the circuit may be designed for performing contact-type communication.In that case, terminals appearing on the sheet surface are found,whereupon an electric power is supplied thereto via a source terminal tothereby put the electronic circuit chip into operation for allowingcommunication of information to be carried out via a communicationterminal.

FIG. 2 is a view showing a configuration of a manufacturing apparatusfor manufacturing the sheet 11 according to the instant embodiment.

In the figure, reference numeral 21 denotes a device or unit for writinginformation in the electronic circuit chip 13. Numeral 22 denotes adevice or unit for mounting the electronic circuit chip 13 on the sheet11. Numeral 23 denotes a device or unit for printing visible informationon the sheet. Numeral 24 denotes a scanner instrument or unit designedfor scanning the surface and the internal of the sheet.

Reference numeral 25 denotes a unit which is in charge of controllingthe information processing as well as operations of the devices or unitsmentioned above.

Next, referring to FIG. 3 which shows a flow chart for illustrating aprocedure of manufacturing the sheet 11 according to the instantembodiment of the invention, description will be made of the sheetmanufacturing procedure.

At first, contents to be printed on the sheet are encrypted by theprocessing unit 25 (step 31). Subsequently, the encrypted information iswritten in the electronic circuit chip 13 by means of the write unit 21(step 32). The electronic circuit chip 13 mentioned above is thenmounted on the sheet 11 by using the mounting unit 22 (step 33).Finally, the surface information 12 is printed on the sheet 11 by usingthe printer unit 23 (step 34). Then, the sheet is finished.

In this conjunction, it should be mentioned that although theinformation is printed in the case of the instant embodiment, any otherappropriate methods may equally be resorted to so far as the visibleinformation can be displayed.

Next, description will turn to a method of detecting a forged sheet byreference to FIGS. 4 to 6. A hardware structure of a forged sheetchecking system is shown in FIG. 4, while a software structure of theforged sheet checking system is shown in FIG. 5. FIG. 6 shows a flowchart for illustrating a forged sheet checking procedure according tothe instant embodiment of the invention.

At first, a control module 52 issues a command to a transmitter unit 41for commanding it to send a radio wave toward the sheet 11 for therebyfeeding an electric power to the sheet 11 (step 61). The electroniccircuit chip 13 supplied with electric power through the medium of theradio wave sends out the information stored therein by way of theantenna 15, the signal as sent out being received by a receiver unit 42(step 62). The control module 52 transfers the information from thereceiver unit 42 to a decrypting module 53 which responds thereto bydecrypting the information (step 63).

A scanner unit 43 scans the surface of the sheet 11 and the internalstructure thereof (step 64). The control module 52 transfers the imageor the like information as acquired to the processing module 55 whichresponds thereto by executing information processing such as imageprocessing or the like (step 65).

A discriminating module 54 compares the decrypted informationoriginating in the electronic circuit chip 13 and transferred from thedecrypting module 53 with the information acquired by scanning the sheet11 and transferred from the processing module 55 (step 66). When boththe data coincide with each other, it is decided that the information 12on the sheet surface is genuine, whereas in case both the data differfrom each other, then decision is made that the information 12 on thesheet surface is counterfeit (step 67).

The control module 52 causes the output unit 44 to generate displayinformation indicative of the result of the decision made by thediscriminating module 54 or alternatively causes the other means tooutput the information indicative of the decision output of thediscriminating module.

The operations and the processings described above by reference to FIGS.5 and 6 can be realized by executing a program stored in the memory 46by means of the CPU 45.

In the case of the instant embodiment, the information 12 inherent tothe sheet surface, i.e., the sheet-inherent information, is encrypted tobe stored in the electronic circuit chip 13 upon manufacturing of thesheet, as described hereinbefore by reference to in FIG. 3. In case theinformation 12 on the sheet surface is altered or falsified, theinformation 12 becomes different from that resulting from the decryptionof the encrypted information stored in the electronic circuit chip 13.Accordingly, with the aid of the forgery checking system 47, thealteration of the information on the sheet surface can be detected bycomparing both the information. In this conjunction, it is noted thatrewriting of the information stored in the electronic circuit chip 13 soas to have the same content as the information of the sheet surfacehaving been altered is practically impossible because the cypher has tobe solved. In this manner, the teaching of the invention incarnated inthe instant embodiment is effective for preventing the alteration of thesheet surface information.

In the encryption described above, when the information stored in theelectronic circuit chip is important or the volume of the information islarge, the public key cryptosystem should preferably be adopted whilethe common key cryptosystem may advantageously be employed in the casewhere the authenticity of the sheet must be checked at a high speed.When the public key cryptosystem is adopted, the memory as required maybe of a small capacity because the length of the key is short with highsecurity being ensured because of impossibility of estimating theencrypting key from the key for decryption. On the other hand, thecommon key cryptosystem allows the decryption of data to be speedilyperformed.

It should further be added that when an only-once-writable electroniccircuit chip is used as the electronic circuit chip 13 for storing theinformation not encrypted, rewriting of the information stored in thatelectronic circuit chip can be prevented, which is thus effective forpreventing the sheet from being altered.

Further, by encrypting the information and writing it in theonly-once-writable electronic circuit chip, there can be realized afurther fortified rewrite protecting means effective for preventing theforgery of the sheet.

According to the teaching of the invention incarnated in the instantembodiment, not only the information common to the sheets of a samespecies such as the information of watermark, pattern and/or the likebut also the information inherent to the individual sheets,respectively, such as security number or the like is written in theelectronic circuit chip. Accordingly, even if a plurality of sheetshaving the visible information which coincides with that stored in theelectronic circuit chip could be reproduced from a given sheet, then theinherent information such as the bond ID numbers of the reproducedsheets are identical with one another. Consequently, in case thecounterfeit sheets are mass-produced, there arises contradiction orcontradictiousness that the sheets of the same ID number existsimultaneously at different places or locations, which can readily leadto revelation of the counterfeit reproduction of the sheet. In thatcase, the ID number of the reproduced sheets may be registered in acomputer 49 connected to the forgery checking system 47 via a network 48to thereby make it impossible to use the reproduced sheets subsequently.In this way, counterfeit reproduction of the sheet can effectively besuppressed.

Furthermore, in the case of the instant embodiment of the invention, thephysical or chemical information of the electronic circuit chip 13 isencrypted to be stored in the electronic circuit chip. Since muchadvanced technique is required for manufacturing the electronic circuitchip 13 in a very fine or miniature structure, reproduction of suchelectronic circuit chip is rendered impossible by managing the chipmanufacturing technology by the manufacturer or the issuer of the sheet.Even if the other portion of the sheet 11 than the electronic circuitchip 13 should be reproduced with the information stored in theelectronic circuit chip being reproduced, it is yet possible to detectthe counterfeit reproduction of the electronic circuit chip by comparingthe information concerning the size or dimensions of the electroniccircuit chip as obtained by measurement with the information stored inthe electronic circuit chip by means of the forgery checking system 47.

At this juncture, it should be mentioned that measurement of the size ofthe electronic circuit chip is not restricted to the straightforwardmeasurement based on the image information but may be performedindirectly on the basis of the radio wave reception range. By way ofexample, a plurality of fine electronic circuit chips of miniature sizeare mounted in an array as closely as possible on the sheet within apredetermined region. In that case, when a number of radio wavescorresponding to that of the electronic circuit chips are received fromthe predetermined region of the sheet upon reception of the signals fromthese electronic circuit chips, it can then be decided at the least thatthe size of the electronic circuit chip is smaller than the prescribedone. In this conjunction, it is to be mentioned that manufacturing ofthe counterfeit electronic circuit chip in the substantially same smallsize as the normal one encounters a great difficulty. Accordingly, evenif the information stored in the electronic circuit chip could bereproduced, it is nevertheless impossible to mount a same number of thecounterfeit fine electronic circuit chips within the predeterminedregion. This feature of the instant embodiment of the invention isequally effective for prevention of the counterfeit reproduction of thesheet.

As is apparent from the above, the teachings of the invention incarnatedin the instant embodiment are very effective for the prevention offorgery such as alteration, counterfeit reproduction thereof and thelike.

In the foregoing description, it has been presumed that the information12 recorded on the sheet surface is used as the visible informationcarried by the sheet. However, the invention is never restricted theretobut any type of information can be made use of so far as it is visible.By way of example, visible information impressed internally of the sheetsuch as, for example, watermark may be used to this end.

Furthermore, although it has been described that the physical orchemical information employed is that of the electronic circuit chip.However, the physical or chemical information of other sheet constituentelements which can discriminatively be identified and which aredifficult to fabricate may be used. More specifically, in the case wherethe material of the sheet is paper, information of the paper fibers maybe used as the information of concern or alternatively an discernibleobject which is difficult to manufacture may be embedded in the sheet sothat information thereof can be used.

(Second Embodiment)

Next, description will be made of a second embodiment of the presentinvention.

According to the teachings of the invention incarnated in the instantembodiment, information of relative position of an externallydiscernible sheet constituent element relative to the electronic circuitchip is encrypted to be stored in the electronic circuit chip 13. Bycomparing this relative position information with the relative positioninformation acquired by measuring or scanning the sheet 11 actually,check is performed as to whether or not the sheet is a forged one.

At first, reference is made to FIG. 7 which shows discernible sheetconstituent elements and relative position information of the sheetconstituent elements relative to the electronic circuit chip. In thefigure, reference numeral 71 designates a side of the sheet 11 andnumeral 72 designates a relative position of the side 71 relative to theelectronic circuit chip 13. Further, relative position information ofvisible object 73 on the sheet surface such as patterns or the like isdesignated by numeral 74 while the relative position information ofconstituent elements 75 resident internally of the sheet such as paperfibers relative to the electronic circuit chip is designated by numeral76 with relative position information of another electronic circuit 77to the electronic circuit chip being designated by reference numeral 78.At least one of the relative position information 72, 74, 76 and 78mentioned above is stored in the electronic circuit chip 13.

Now, reference is made to FIG. 8 which illustrates a procedure ofmanufacturing the sheet according to the instant embodiment of theinvention.

After the electronic circuit chip 13 has been mounted on the sheet 11 ata random position (step 81), printing is performed on the sheet 11 (step82). Then, by scanning the sheet 11, the relative position informationdescribed above is acquired (step 83), whereon the information asacquired is encrypted (step 84) to be subsequently written in theelectronic circuit chip 13 mounted (step 85). Parenthetically, in thecase of the instant embodiment of the invention, it is presumed that thesheet 11 made of paper is employed. However, material of the sheet 11 isnot restricted to paper but other type of sheet can be employed so faras the material thereof is not homogeneous. In the procedure now underconsideration, mounting of the electronic circuit chip 13, writing ofthe information in the electronic circuit chip 13, printing on the sheet11 and scanning or measurement are carried out by using the devices orunits employed in carrying out the first embodiment of the invention.

With the arrangement according to the instant embodiment describedabove, even if the electronic circuit chip 13 can be reproduced, it isdifficult to embed the reproduced electronic circuit chip 13 in thesheet 11 made of nonhomogeneous material at the same position as theposition where the genuine electronic circuit chip 13 is embedded in theauthentic sheet 11, involving an error in respect to the mountingposition. For this reason, the manufacturer of the electronic circuitchip 13 and the issuer of the sheet 11 can easily perform the check ofthe sheet without need for enhancing the accuracy for the mountingposition of the electronic circuit chip 13, whereas for the forgers,high-precision techniques will be required for mounting the electroniccircuit chip and for controlling the printing position. This feature iseffective for preventing the forgery of the sheet.

Further, in the instant embodiment of the invention, the relativeposition information of constituent element located very closely to theelectronic circuit chip may be included in the information to be storedupon storage of the relative position information 72, 74, 76 or 78 inthe electronic circuit chip 13. In that case, it is expected thatfrequency at which contraction/expansion or breakage of the sheet occursin a gap area intervening between the electronic circuit chip 13 and thesheet constituent element positioned closely thereto can be decreased,and at the same time the accuracy of the position information can beincreased. For these reasons, in checking the sheets as to theauthenticity thereof, the detection accuracy can be enhanced with theprobability of erroneous detection or recognition being decreased.

(Third Embodiment)

Now, a third embodiment of the present invention will be described.

The instant embodiment differs from the first or second embodiment inthat the information to be stored in the electronic circuit chip 13 isnot encrypted but stored intactly as plaintext which is affixed with adigital signature. The digital signature gives the guarantee that therelevant text has not been falsified. Only the person who knows aprivate key is capable of creating the digital signature. A forger whodoes not know the private key may falsify or forge the plaintext but heor she can not newly create a digital signature that ensures theauthenticity of the plaintext. Thus, falsification of the sheet can bedetected by checking the authenticity of the digital signature.

FIG. 9 shows a flow chart for illustrating a forged sheet checkingprocedure according to the instant embodiment, which procedure isexecuted by the CPU 45 in the system configuration shown in FIG. 4. Theprocessing illustrated in FIG. 9 can be realized by executing theprogram stored in the memory 46 by means of the CPU 45.

At first, the information stored in the electronic circuit chip 13 isread out by the relevant receiver unit 42 (step 91). For acquiring theinformation to be compared with the information as read out, the sheet11 is scanned by the scanner unit 43 (step 92), and informationprocessing such as an image processing or the like is carried out by theprocessing module 55.

The discriminating module 54 compares both the information acquired inthe steps 91 and 92, respectively (step 93). When both the informationdiffer from each other, the forgery checking system 47 decides that thesheet 11 is a forged one (step 94). On the other hand, when coincidenceis found between both the information, the affixed digital signatureinformation is transferred to the discriminating module 54 by thecontrol module 52, whereon authenticity of the digital signature isverified (step 95). When the verification results in that the digitalsignature is justifiable, the forgery checking system 47 decides thatthe sheet is an authentic one. On the contrary, when the result of theverification is unjustifiable, the forgery checking system 47 decidesthat the sheet is a forged one (step 96).

In this way, according to the teaching of the invention incarnated inthe instant embodiment, forgery of the sheet can be detected already atthe stage of the step 94, which means that the steps 95 and 96 can beomitted. Thus, it is expected that the time taken for checking thecounterfeitness of the sheet can be shortened when compared with thecase where the encrypted information is used as described hereinbeforein conjunction with the first or second embodiment.

Further, in the system according to the instant embodiment, whentransmission error takes place in the course of communication,verification of the digital signature will result in incorrectness. Inthat case, appropriate measurement such as rereading or the like can betaken. Thus, acquisition of erroneous information can be avoided.

As described previously, in the case of the instant embodiment, theplaintext information affixed with digital signature is stored in theelectronic circuit chip 13 intactly without undergoing encryption, beingaffixed with the digital signature. It should however be mentioned thatthe information encrypted and affixed with the digital signature mayequally be stored in the electronic circuit chip.

Furthermore, in the case of the instant embodiment, the digitalsignature is affixed for assuring that the information is not altered.However, instead of the digital signature, a falsification detectingcode based on the common key cryptosystem may be affixed. Since thecommon key cryptosystem allows the verification processing to beexecuted at a higher speed when compared with the public keycryptosystem which is primarily adopted for the digital signature, thetime required for detection of the forged sheet can further beshortened.

(Fourth Embodiment)

Next, referring to FIG. 4 and FIG. 10, a fourth embodiment of thepresent invention will be described.

In the case of the instant embodiment, genuineness of the sheet isdecided synthetically by adopting a sheet 11 in which a plurality ofelectronic circuit chips 13 are incorporated.

FIG. 10 shows a flow chart illustrating a processing procedure accordingto the instant embodiment. The processing procedure illustrated in FIG.10 can be realized by executing a program stored in the memory 46 bymeans of the CPU 45.

At first, the sheet 11 is scanned by the scanner unit 43 to therebyacquire the information about the number and the positions of theelectronic circuit chips 13 incorporated in the sheet 11 (step 101). Insuccession, internal information stored in the individual electroniccircuit chips 13 is acquired by means of the receiver unit 42 (step102), whereon elementary information such as the number, accuracy,priorities and the like of the information are evaluated properly tothereby deduce a threshold value. The sheet 11 is scanned (step 104) anda counter value is set to “0” (zero) (step 105). The informationacquired in the step 102 is compared with the information acquired inthe steps 104 on a per-information basis (step 106). When difference isfound between both the information (step 107), the counter value isincremented by “1” (one) (step 108). When comparison has completed forall the information (step 109), it is checked whether or not the countervalue is smaller than the threshold value inclusive (step 10A). Unlessthe counter value exceeds the threshold value, it is decided that thesheet is genuine, whereas when the counter value exceeds the thresholdvalue, decision is made that the sheet is a forged one (step 10A).

According to the invention incarnated in the instant embodiment, evenwhen the sheet is wrinkled, bent or broken in the vicinity of theelectronic circuit chips 13, bringing about deviation in the relativepositions between the electronic circuit chips 13 and the peripheries,the frequency or possibility of the genuine sheet being mistaken for theforged sheet can be reduced.

Parenthetically, an appropriate evaluation method (evaluatingexpression) and a proper threshold value may previously be determined onthe basis of the various internal information (e.g. the elementaryinformation such as the number, accuracy, priority and the like of theinformation) stored in the electronic circuit chips 13 so that thedetecting unit can make decision upon checking of the sheet as to theauthenticity or genuineness in accordance with the predeterminedevaluation method mentioned above.

(Fifth Embodiment)

Now, a fifth embodiment of the present invention will be described byreference to FIG. 14.

According to the teaching of the invention incarnated in the instantembodiment, the identification number inherent to the electronic circuitchip 13 is stored in the electronic circuit chip, and additionallyinformation intrinsic to the sheet 11 or the electronic circuit chip 13or the combination thereof is stored in a storing means other than theabove-mentioned electronic circuit chip while establishingcorrespondency to the identification number of the electronic circuitchip mentioned above.

Now, description will turn to a method of detecting a forged sheet byreference to FIG. 4, FIG. 5 and FIG. 14. A hardware structure of aforgery checking system in carrying out the method according to theinstant embodiment is shown in FIG. 4, while a software structure of theforgery checking system is shown in FIG. 5. FIG. 14 shows a flow chartfor illustrating a forged sheet checking procedure according to theinstant embodiment of the invention.

At first, the control module 52 issues a command to the transmitter unit41 for sending a radio wave in the direction toward the sheet 11 forthereby feeding an electric power to the sheet 11 (step 61). Theelectronic circuit chip 13 supplied with the electric power through themedium of the radio wave sends out the inherent information storedtherein by way of the antenna 15, the signal as sent out being receivedby the receiver unit 42 (step 62). The control module 52 issues acommand to the transmitter unit 41 to send the inherent information tothe computer 49 connected via the network 48 (step 141). Upon receptionof the inherent information (step 142), the computer 49 extracts theinformation corresponding to the received inherent information fromamong the information inherent to the sheet 11 or the electronic circuitchip 13 or the combination thereof held in correspondence to theinherent information, to thereby send the extracted information to theforgery checking system 47 after encryption (step 143). The receiverunit 42 receives the information from the computer 49 (step 144) totransfer it to the control module 52. The control module 52 in turntransfers the information to the decrypting module 53 which respondsthereto by decrypting the information (step 63).

The scanner unit 43 scans the surface of the sheet 11 and the internalstructure thereof (step 64). The control module 52 transfers the imageinformation and others as acquired to the processing module 55 whichresponds thereto by executing the information processing such as imageprocessing or the like (step 65).

The discriminating module 54 compares the decrypted informationtransferred from the computer 49 by way of the decrypting module 53 withthe information acquired by scanning the sheet 11 as transferred fromthe processing module 55 (step 66). When both the data coincide witheach other, it is then decided that the information 12 on the sheetsurface is authentic, whereas in case both the data differ from eachother, decision is then made that the information 12 on the sheet iscounterfeit (step 67).

The control module 52 commands the output unit 44 to output theinformation which conforms with the result of the decision made by thediscriminating module 54 through a display or the like means.

The operations and the processings described above by reference to FIGS.5 and 14 can be realized by executing a program stored in the memory 46by means of the CPU 45.

In the case of the instant embodiment, the information inherent to thesheet 11 or the electronic circuit chip 13 or the combination thereof isstored in the computer 49. Consequently, even when an unwritableelectronic circuit chip is employed, forgery can equally be preventedsimilarly to the case of the first, second, third or fourth embodimentof the present invention. As a result of this, the circuit scale of theelectronic circuit chip can be made smaller and thus the chip can bemanufactured inexpensively in a reduced size. Thus, the inventionincarnated in the instant embodiment is effective for realizing theprevention against forgery of the sheet at a low cost.

Parenthetically, it should be added that although the computer 49 isemployed as the destination for storing the information inherent to thesheet 11 or the electronic circuit chip 13 or the combination thereof inthe case of the instant embodiment of the present invention, it goeswithout saying that a storing means other than the computer such as aflash memory card, an electronic circuit chip, etc. may be used.

By way of example, a plurality of inexpensive unwritable electroniccircuit chips 13 storing the number inherent to the sheet 11 may beincorporated in the sheet 11 while the information inherent to the sheet11 or the electronic circuit chip 13 or the combination thereof may bestored in one writable electronic circuit chip. In that case,substantially same degree of readability as in the case where aplurality of expensive writable electronic circuit chips are mounted canbe realized without using a plurality of expensive writable electroniccircuit chips.

Further, it is also possible to combine the first to fifth embodimentsdescribed heretofore.

(Sixth Embodiment)

Next, description will be directed to a sixth embodiment of the presentinvention.

FIG. 11 is a view showing sheets and a configuration of a sheetmanagement system, and FIG. 13 is a flow chart for illustrating a sheetmanagement procedure. By referring to FIGS. 11 and 13, description willbe made of a sheet managing method according to the instant embodiment.

Referring to FIG. 11, the sheet managing method according to the instantembodiment will be described. Reference numeral 111 denotes atransmitter unit which is designed for feeding an electric power to thesheet through the medium of a radio wave and sending a command to thesheet. The transmitter unit is disposed movably along the direction inwhich the sheets are stacked. Numeral 112 denotes a receiver unitdesigned for receiving signals emitted from the sheets. Numeral 113denotes an output unit designed for outputting management statuses ofthe sheets. Numeral 114 denotes a control unit designed for controllingthe transmitter unit 111, the receiver unit 112 and the output unit 113.Numeral 115 generally denotes a system designed for management of thesheets. Mounted on each sheet 116 at a peripheral portion thereof are anantenna 117, a capacitor 118 and an electronic circuit chip 119,respectively, for the purpose of enabling contactless communication withthe management system 115.

The electronic circuit chip 119 mounted on the sheet 116 incorporatestherein a random number generating means (random number generatingprogram executed by the CPU or a dedicated circuit), a storing means (aregister, a memory or the like) for storing the inherent information(e.g. visible information such as an identification number, species,face amount, etc.), a signal transmitting means and a signal receivingmeans.

When the radio wave is applied to the antenna 117 from the transmitterunit 111, a potential difference is induced in the antenna 117, as aresult of which electric charges are stored in the capacitor 118. Thus,electric power is supplied to the electronic circuit chip 119 (step135). The electronic circuit chip 119 then generates a random number(step 131). On the basis of the random number as generated, a signalindicative of the above-mentioned information inherent to the sheet 116is intermittently sent out with every transmission interruption periodchanging at random (step 132). Upon reception of this signal by thereceiver unit 112 (step 136), the control unit 114 performs recognitionand registration of the relevant sheet 116 (step 137), whereon a stopcommand valid to only that sheet 116 is issued from the transmitter unit111 (step 138). Upon reception of the stop command (step 133), the sheet116 stops the transmission from that time on (step 134).

In case the system can not correctly receive the signals sent from theplural sheets due to superposition of the signals (step 136), themanagement system 115 does not issue the stop command but waits for tillthe signal inherent to the sheet is sent again. Since the inherentsignal as sent intermittently at random interval, the signals sent fromall the sheets can be received after lapse of a predetermined timeperiod (step 139). The control unit 114 manages the sheets with theinformation inherent to the individual sheets.

The management statuses of the sheets are outputted through the outputunit 113.

By using the transmitter unit 111 having the radio wave coverage limitedand recognizing the sheets while moving the transmitter unit along thedirection in which the sheets are stacked, the ratio at which thesignals emitted from the plural sheets are received concurrently can bereduced. Thus, management of the plural sheets can be carried out at ahigh speed with enhanced reliability.

As can now be appreciated, by virtue of the arrangement according to theinstant embodiment of the invention, a large number of sheets ofdifferent species and/or sizes can be managed in the stacked state at astretch with high reliability with the apparatus of a small size.

By way of example, those sheets which are required to be managed withhigh reliability such as registered mail, paper currency, certificate ofshare/stock, gift certificate, etc. can individually be managed in thestate stacked or put together, being bundled by a belt or a cord,packaged or contained in a bag, which contributes to reduction of thetime taken for the management of the sheets as well as prevention ofmissing and stealage.

Parenthetically, the sheet according to the instant embodiment of theinvention is not restricted to the structure described above. Namely,the sheet is required to be equipped with an information hold unit 121,a transmitter unit 122 and a receiver unit 123, as is shown in FIG. 12,but need not necessarily include the antenna 117, the capacitor 118 andthe electronic circuit chip 119.

Although the embodiments of the invention have been described on thepresumption that they are applied to managements of sheets and cards,the present invention is never restricted thereto. Other objects havingvisible information may be handled without departing from the spirit andscope of the present invention.

INDUSTRIAL APPLICABILITY

As is apparent from the foregoing description, according to theteachings of the present invention, it is possible to make it difficultto forge or counterfeit the sheet carrying the visible information suchas bond, gift certificate, paper currency, document and the like.Besides, even if the sheet should be forged, detection thereof can befacilitated.

Furthermore, a large number of sheets differing one another in respectto the species and the size can speedily be managed at a stretch withhigh reliability by the apparatus of a small scale.

1. A system for detecting forgery of a sheet, said system including aforgery detecting device and a memory device which are connected via anetwork, said forgery detecting device including a control unit, ascanning unit and a discriminating unit, said sheet includinginformation obtainable by said scanning unit and an electronic circuitchip which stores a unique number, said memory device storing uniqueinformation correlated with said unique number, said unique informationbeing unique to said sheet, said electronic circuit chip or acombination of the sheet and the electronic circuit chip, said controlunit reading out said stored unique number from said electronic circuitchip provided in said sheet, said control unit obtaining from saidmemory device said stored unique information correlated with said uniquenumber and unique to said sheet, said electronic circuit chip or acombination of the sheet and the electronic circuit chip, said scanningunit acquiring said information obtainable by said scanning unit, byscanning said sheet, and said discriminating unit comparing said uniqueinformation unique to said sheet, said electronic circuit chip or acombination of the sheet and the electronic circuit chip with saidinformation obtained by scanning said sheet to discriminativelydetermine whether the information acquired from said sheet is authentic.2. A forgery detecting system according to claim 1, wherein said forgerydetecting device includes a transmitter and a receiver, said transmitteris responsive to an instruction from said control unit to supplyelectric power to said sheet by transmission of an electric wave, saidelectronic circuit chip provided in said sheet is responsive to supplyof electric power by said electric wave to transmit said unique numberstored therein, and said receiver is responsive to reception of saidtransmitted unique number to output the same to said control unit.
 3. Aforgery detecting system according to claim 1, wherein said memorydevice encrypts the information unique to said sheet, said electroniccircuit chip or a combination of the sheet and the electronic circuitchip when taken out by said control unit, said forgery detecting deviceincludes a decrypting unit, and said decrypting unit decrypts theinformation unique to said sheet, said electronic circuit chip or acombination of the sheet and the electronic circuit chip when taken outby said control unit and outputs the decrypted information to saidcontrol unit.
 4. A forgery detecting system according to claim 1,wherein said memory device is provided in said sheet having saidelectronic circuit chip.
 5. A forgery detecting system according toclaim 1, wherein said forgery detecting device comprises an output unit,and said control unit outputs a result of said discrimination by saiddiscriminating unit to said output unit.
 6. A forgery detecting systemaccording to claim 1, wherein said forgery detecting device comprises animage processing unit, and said image processing unit image-processesinformation from said sheet by scanning the sheet, and outputs a resultof the image-processing therefor to said discriminating unit.